Aromatic trisanhydrides

ABSTRACT

Aromatic trisanhydrides of the formula (I) ##STR1## wherein R is hydrogen, C 1  -C 4  alkyl or aryl are useful for the synthesis of star-branched and star-burst polyester-imides and polyesterimide-amides and as curing agents for epoxy resins, phenolics and polyesters.

This is a divisional of Ser. No. 07/667,718, filed Mar. 11, 1991 nowU.S. Pat. No. 5,241,082.

BACKGROUND OF THE INVENTION

There is a continual emphasis on improved high temperaturecharacteristics for resinous materials and for curing agents which willimprove the characteristics of already existing polymeric materials.

U.S. Pat. No. 3,182,073 describes trimellitic anhydride derivativesuseful as curing agents for various resinous materials such aspolyesters, epoxy resins and the like and also as substituents forpreparing polyimides. U.S. Pat. No. 3,182,073 does not disclose thearomatic trisanhydrides of the present invention.

Accordingly, it is an object of the present invention to providearomatic trisanhydrides which are useful as curing agents for epoxyresins, phenolics, polyesters and other oligomers and polymerscontaining hydroxyl groups and as monomer for the synthesis ofstar-branched polyimide-ester and polyimide-amides with radial symmetry.

It is a further object of the present invention to provide polymericmaterials exhibiting high thermo-oxidative stability, Tg, toughness andmechanical strength.

Various other objects and advantages of this invention will becomeapparent from the following description thereof.

SUMMARY OF THE INVENTION

The present invention relates to aromatic trisanhydrides having radialsymmetry for use as monomers in the synthesis of star-branchedpolyester-imides and polyesterimide-amides and as curing agents forepoxy resins, phenolics and polyesters.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to aromatic trisanhydrides of the formula(I) ##STR2## wherein R is hydrogen, C₁ -C₄ alkyl and aryl.

Aryl includes phenyl, benzyl, α-naphthyl, β-naphthyl, meta- andpara-methylphenyl and trifluoromethylphenyl. Aryl is preferably phenyl.Alkyl is preferably methyl.

The trisanhydrides of this invention can be prepared by reaction oftrimellitic anhydride chloride with trisphenols as exemplified in thereaction scheme below: ##STR3## Some of the trisphenols having radialsymmetry are commercially available, e.g., phloroglucinol,1,1,1-tris(hydroxyphenyl)-ethane. Others may be obtained by well knownprocesses, such as condensation of phenols with compounds having thetrichloromethyl group.

The preparation of the trisanhydrides according to the present inventionmay be carried out in anhydrous solvents, such as ether,tetrahydrofuran, acetone, methyl ethyl ketone, benzene, toluene,ethylene dichloride, etc., in the presence of tertiary amines, such aspyridine, triethylamine, etc. Preferably, the tertiary amine is added toa solution of trimellitic anhydride chloride and a tris-phenol, cooledto 0°-5° C. with subsequent stirring of the reaction mixture at 15°-75°C. for 0.5-6 hours. The resulting tris-anhydride may be separated byprecipitation in a solvent in which tertiary amine hydrochlorides aresoluble, such as methanol, ethanol, 2-propanol.

Multifunctional, cross-linkable polyester-imide oligomers are formed byreacting:

1) 1 mole of an aromatic trisanhydride of the formula (I),

2) 3 moles of diamine having terminal amine groups, and

3) 3 moles of an acid anhydride containing reactive groups, for example,maleimides, norbornene, etc.

The reaction is carried out by mixing the reactants in a suitablesolvent in the presence of an inert atmosphere. The reaction can beexemplified in the reaction scheme below: ##STR4##

The oligomers can be crosslinked to form polymers which are processable,tough and possess excellent thermo-oxidative properties.

Suitable diamines include o-, m- and p-phenylenediamine,diaminotoluenes, such as 2,4-diaminotoluene,1,4-diamino-2-methoxybenzene, 2,5-diaminoxylene,1,3-diamino-4-chlorobenzene, 4,4'-diaminodiphenylmethane,4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl thioether,4,4'-diaminodiphenylsulphone, 2,2'-diaminobenzophenone,4,4'-diaminodiphenylurea and 1,8- or 1,5-diaminonaphthalene;2,6-diaminopyridine, 2,4-diaminopyrimidine, 2,4-diamino-s-triazine, di-,tri-, tetra-, hexa-, hepta-, octa- and deca-methylenediamine,2,2-dimethylpropylenediamine, 2,5-dimethylhexamethylenediamine,4,4-dimethylheptamethylenediamine, 3-methylheptamethylenediamine,3-methoxyhexamethyldiamine, 2,11-diaminododecane, 2,2,4- and2,4,4-trimethylhexamethylenediamine, 1,2-bis-(3-aminopropoxy)ethane,N,N'-dimethylethylenediamine and N,N'-dimethyl-1,6-diaminohexane as wellas the diamines of the formula H₂ N(CH₂)₃ O(CH₂)₂ O(CH₂)₃ NH₂ and H₂N(CH₂)₃ S(CH₂)₃ NH₂ ; 1,4-diaminocyclohexane,1,4-bis-(2-methyl-4-aminopentyl)-benzene and1,4-bis-(aminomethyl)-benzene.

Preferably, the diamine is 4,4'-diaminodiphenyl ether,1,4-phenylenediamine or 1,3-phenylenediamine.

Suitable compounds of component (c) include5-norbornen-endo-2,3-dicarboxyl anhydride (nadic anhydride); allyl nadicanhydride; methyl nadic anhydric, maleic anhydride and citraconicanhydride.

The preferred component (c) is 5-norbornene-endo-2,3-dicarboxylanhydride.

Multifunctional, cross-linkable polyesterimide-amides are formed byreacting:

1) 1 mole of an aromatic trisanhydride of the formula (I),

2) 3 moles of diamine having terminal amine groups, and

3) 3 moles of an acid chloride containing reactive groups, for example,maleimides, norbornene, etc.

The reaction is carried out by mixing the reactants in a suitablesolvent in the presence of an inert atmosphere. The reaction can beexemplified in the reaction scheme below: ##STR5##

The oligomers can be crosslinked to form polymers which are processable,tough and possess excellent themo-oxidative properties.

Suitable diamines are those set forth hereinabove for the preparation ofthe polyester-imide oligomers.

Suitable compounds of component (c) include nadic benzoylchloride,dinadic benzoylchloride; ortho-, meta- or para-maleimido benzoic acidchloride; ortho-, meta- or para-nadicimido benzoic acid chloride andvinyl benzoic acid chloride.

The polyester-imides and polyesterimide-amides are suitable for themanufacture of shaped articles of very diverse types, such as fibres,films sheets, coating compositions, foams, laminating resins, compositematerials, molding powders, pressed articles and the like, in a mannerwhich is in itself known. The polymers according to the invention canalso be processed easily from the melt and are distinguished by goodmechanical, electrical and thermal properties as well as, in general, bygood solubility in organic solvents, such as N,N-dimethylacetamide,N,N-dimethylformamide and N-methyl-2-pyrrolidone.

The invention further relates to a resin formulation comprising apolymer containing hydroxyl groups and an aromatic trisanhydride of theformula I described hereinabove.

The polymers useful in the formulation of the present invention includeepoxy resins, phenolics and polyesters.

Suitable epoxy resins include virtually any epoxide resin having onaverage at least two 1,2-epoxide groups per molecule.

The following are examples of these:

I) polyglycidyl and poly-(β-methylglycidyl) esters which can beobtained, for example, by reacting a compound containing at least twocarboxyl groups in the molecule with epichlorohydrin, glyceroldichlorohydrin or β-methyl epichlorohydrin in the presence of bases.Examples of compounds having at least two carboxyl groups in themolecule are saturated aliphatic dicarboxylic acids, such as oxalicacid, malonic acid, succinic acid, α-methylsuccinic acid, glutaric acid,adipic acid, pimelic acid, azelaic acid, sebacic acid or dimerizedlinoleic acid; or unsaturated aliphatic dicarboxylic acids, such asmaleic acid, mesaconic acid, citraconic acid, glutaconic acid oritaconic acid; or cycloaliphatic dicarboxylic acids, such ashexahydrophthalic, hexahydroisophthalic or hexahydroterephthalic acid ortetrahydrophthalic, tetrahydroisophthalic or tetrahydroterephthalic acidor 4-methyltetrahydrophthalic acid, 4-methylhexahydrophthalic orendomethylenetetrahydrophthalic acid; or aromatic dicarboxylic acids,such as phthalic, isophthalic or terephthalic acid; or copolymers ofmeth(acrylic acid with copolymerizable vinyl monomers, for example the1:1 copolymers of methacrylic acid with styrene or with methylmethacrylate. Examples of tricarboxylic and higher carboxylic acids areespecially aromatic tricarboxylic or tetracarboxylic acids, such astrimellitic acid, trimesic acid, pyromellitic acid orbenzophenonetetracarboxylic acid, and also dimerized or trimerized fattyacids such as are available commercially, for example, under the namePripol®.

II) Polyglycidyl and poly-(β-methylglycidyl) ethers which can beobtained, for example, by reacting a compound containing at least twoalcoholic hydroxyl groups and/or phenolic hydroxyl groups in themolecule with epichlorohydrin, glycerol dichlorohydrin or β-methylepichlorohydrin under alkaline conditions or in the presence of an acidcatalyst with subsequent treatment with alkali. Examples of compoundshaving at least two alcoholic hydroxyl groups and/or phenolic hydroxylgroups in the molecule are aliphatic alcohols, such as ethylene glycol,diethylene glycol and higher poly-(oxyethylene) glycols,propane-1,2-diol, propane-1,3-diol or higher poly-(oxypropylene)glycols, butane-1,4-diol or higher poly-(oxybutylene) glycols,pentane-1,5-diol, neopentyl glycol (2,2-dimethylpropanediol),hexane-1,6-diol, octane-1,8-diol, decane-1,10-diol ordodecane-1,12-diol; hexane-2,4,6-triol, glycerol,1,1,1-trimethylolethane, 1,1,1-trimethylolpropane, pentaerythritol,sorbitol or polyepichlorohydrins; or cycloaliphatic alcohols, such as1,3-dihydroxycyclohexane, 1,4-dihydroxycyclohexane,1,4-cyclohexanedimethanol, bis-(4-hydroxycyclohexyl)-methane,2,2-bis-(4-hydroxycyclohexyl)-propane or1,1-bis-(hydroxymethyl)-cyclohex-3-ene; or alcohols containing aromaticgroups, such as N,N-bis-(2-hydroxyethyl)-aniline orp,p'-bis-(2-hydroxyethylamino)-diphenylmethane; or mononuclear orpolynuclear polyphenols, such as resorcinol, hydroquinone,bis-(4-hydroxyphenyl)-methane, 2,2-bis-(4-hydroxyphenyl)-propane,brominated 2,2-bis-(4-hydroxyphenyl)-propane, bis-(4-hydroxyphenyl)ether, bis-(4-hydroxyphenyl) sulfone,1,1,2,2-tetrakis-(4-hydroxyphenyl)-ethane or novolaks which areobtainable by the condensation of aldehydes, such as formaldehyde,acetaldehyde, chloral or furfuraldehyde, with phenols which areunsubstituted or substituted by alkyl or halogen, such as phenol, thebisphenols described above, 2-methylphenol, 4-methylphenol,4-tert-butylphenol, p-nonylphenol or 4-chlorophenol.

III) Poly-(N-glycidyl) compounds which can be prepared, for example, bydehydrochlorinating reaction products of epichlorohydrin with aminescontaining at least two amino hydrogen atoms. Examples of amines onwhich such epoxy resins are based are aliphatic amines, such ashexamethylenediamine or n-butylamine; cycloaliphatic amines, such as1,4-diaminocyclohexane or bis-aminomethylene-1,4-cyclohexane; aromaticamines, such as aniline, p-toluidine, bis-(4-aminophenyl)-methane,bis-(4-aminophenyl) ether, bis-(4-aminophenyl) sulfone,4,4'-diaminobiphenyl or 3,3'-diaminobiphenyl; or araliphatic amines,such as m-xylylenediamine. The poly-(N-glycidyl) compounds also include,however, triglycidyl isocyanurate, N,diglycidyl derivatives ofcycloalkyleneureas, such as ethyleneurea or 1,3-propyleneurea, andN,diglycidyl derivatives of hydantoins, such as 5,5-dimethylhydantoin.

IV) Poly-(S-glycidyl) compounds, for example di-S-glycidyl derivativesderived from dithiols, such as ethane-1,2-dithiol orbis-(4-mercaptomethylphenyl) ether.

V) Cycloaliphatic epoxy resins or epoxidation products of dienes orpolyenes, such as cycloaliphatic epoxy resins which can be prepared, forexample, by epoxidation of ethylenically unsaturated cycloaliphaticcompounds. Examples of these are1,2-bis-(2,3-epoxycyclopentyloxy)-ethane, 2,3-epoxycyclopentyl glycidylether, diglycidyl cyclohexane-1,2-dicarboxylate, 3,4-epoxycyclohexylglycidyl ether, bis-(2,3-epoxycyclopentyl) ether,bis-(3,4-epoxycyclohexyl) ether,5(6)-glycidyl-2-(1,2-epoxyethyl)-bicyclo[2.2.1]heptane,dicyclopentadiene dioxide, cyclohexa-1,3-diene,3,4-epoxy-6-methylcyclohexylmethyl3',4'-epoxy-6'-methylcyclohexanecarboxylate or 3,4-epoxycyclohexylmethyl3',4'-epoxycyclohexanecarboxylate. It is also possible, however, to useepoxy resins in epoxycyclohexanecarboxylate. It is also possible,however, to use epoxy resins in which the 1,2-epoxy groups are attachedto various heteroatoms or functional groups; such compounds include, forexample, the N,N,O-triglycidyl derivative of 4-aminophenol, theN,N,O-triglycidyl derivative of 3-aminophenol, the glycidylether/glycidyl ester of salicylic acid,N-glycidyl-N'-(2-glycidyloxypropyl)-5,5-dimethylhydantoin or2-glycidyloxy-1,3-bis-(5,5-dimethyl-1-glycidylhydantoin-3-yl)-propane.

Preferred epoxy resin are Bishpenol A diglycidyl ethers,N,N'-tetraglycidyl diamines, glycidyl ethers of phenolaldehydecondensates.

Suitable phenolic resins are those obtained by the condensation ofphenol or substituted phenols. With aldehydes such as formaldehyde,acetaldehyde and furfuraldehyde. Examples of phenols and substitutedphenols are phenol, alkyl-substituted phenols, including cresols,xylenols, p-tert-butylphenol, p-phenylphenol, and nonylphenol. Preferredis the condensation product of phenol and formaldehyde.

Suitable polyesters are those which are derived from dicarboxylic acidsand diols and/or from hydrocarboxylic acids or the correspondinglactones, such as polyethylene terephthalate, polybutyleneterephthalate, poly-1,4-dimethylol-cyclohexane terephthalate,polyhydroxybenzoates as well as block-copolyether-esters derived frompolyethers having hydroxyl end groups.

The epoxy resin formulations of the present invention comprise about 30to about 80 parts by weight of epoxy resin and about 70 to about 20parts by weight of an aromatic trisanhydride of the formula I describedhereinabove.

The polyester resin formulations of the present invention comprise about70 to about 90 parts by weight of a polyester resin and from about 30 toabout 1, preferably about 10 to about 5 parts by weight of an aromatictrisanhydride of formula I described hereinabove.

The amount of the resin and the trisanhydride will vary with theparticular resin and aromatic trisanhydride chosen. The exactformulation for each is well within the ambit of the skilled artisanbased on the guidance provided herein.

The compositions of the invention may also contain other conventionalmodifiers such as extenders, fillers and reinforcing agents, pigments,dyestuffs, organic solvents, plasticizers, tackifiers, rubbers,diluents, latent curing agents and the like. As extenders, reinforcingagents, fillers and pigments which can be employed in the compositionsaccording to the invention there may be mentioned, for example: glassfibers, glass balloons, boron fibers, carbon fibers, cellulose,polyethylene powder, polypropylene powder, mica, asbestos, quartzpowder, gypsum, antimony trioxide, bentones, talc, silica aerogel("Aerosil"), fumed silica, lithopone, barite, calcium carbonate,titanium dioxide, carbon black, graphite, iron oxide, or metal powderssuch as aluminum powder or iron powder. The preferred fillers are glassballoons and fumed silica. The preferred latent curing agent isdicyandiamide. It is also possible to add other usual additives, forexample, agents for conferring thixotropy, flow control agents such assilicones, cellulose acetate butyrate, polyvinyl butyral, stearates andthe like.

A vertical type high-speed agitator, kneading machine, roll machine,ball mill or any other suitable mixing and agitating machine may be usedfor dispersion of the components of the composition of the presentinvention.

The resin compositions in accordance with the present invention areparticularly useful for the preparation of structures for the aerospaceindustry.

The following examples serve to give specific illustrations of thepractice of this invention but they are not intended in any way to limitthe scope of this invention.

EXAMPLE 1 Synthesis of the Trisanhydride I

To the solution of 12.6 g (0.1 mol) of anhydrous phloroglucinol and 63.2g (0.3 mol) of trimellitic anhydride chloride in 300 ml of dry acetonecooled to 0° C. under N₂ 26.1 g of dry pyridine (0.3 m+10% excess) wasadded dropwise (˜1 hour). Afterwards, the reaction mixture was stirredat room temperature for 2 hours and at 50°-55° C. for 0.5 hour. Aftercooling to RT, the mixture was added to 1.5 liters of dry isopropanol,whereupon a fine white precipitate was formed which was washedsequentially with methanol and ether, then dried in vacuum overnight at110° C. The product--an off-white powder--had a melting point of299°-300° C. A yield of 58 g (90%) was obtained. Elemental analysis:calculated for C₃₃ H₁₂ O₅ C: 61.1%, H 1.8%; found: C 60.7%, H 1.6%.Structure of the trisanhydride was also confirmed by IR and NMR.

EXAMPLE 2 Synthesis of the Trisanhydride II (R--CH₃)

To the solution of 30.6 g (0.1 mol) of 1,1,1-Tris(4-hydroxyphenyl)ethaneand 63.2 g (0.3 mol) of trimellitic anhydride chloride in 400 ml of drytetrahydrofuran cooled to 2° C. under N₂ 34 g of triethylamine was addeddropwise (˜1 hour). After that, the reaction mixture was stirred at RTfor 6 hours and precipitated in 2 liters of dry isopropanol. Theprecipitate was washed with methanol and ether. The product--anoff-white powder--had a melting point of 301°-302° C. A yield of 78.5 g(95%) was obtained. Elemental analysis: calculated for C₄₇ H₂₄ O₁₅ : C68.1%, H 2.8%; found: C 67.5%, H 2.5%.

EXAMPLE 3 Synthesis of Star Branched Aromatic Polyester-imide Based onTrisanhydride I

To the solution of 64.8 g (0.1 mol) of the trisanhydride I and 49.2 g(0.3 mol) of 5-norbornene-endo-2,3-dicarboxyl anhydride in 500 ml of drydimethylacetamide (DMAC) cooled to 0° C. under N₂ the solution of 60 g(0.3 mol) of 4-aminophenylether in 500 ml of DMAC was added dropwise (3hours) and the reaction mixture was stirred at room temperatureovernight. Then 300 ml of toluene were added and the mixture refluxeduntil the water was completely eliminated. Toluene was distilled off andthe solution stirred at 150°-155° C. for 6 hours. After cooling, thesolution was precipitated in 5 liters of cold water. Theprecipitate--yellow powder--was washed with water 3 times and dried invacuum at 80° C. The formation of the imide structure in the product wasconfirmed by the presence of characteristic absorptions in IR spectra at1783, 1375 and 717-721 cm⁻¹. The absorption band at 1748 cm⁻¹ may be dueto overlapping of the absorptions from the imide structure and the estergroup. The oligomer formed a clear melt at 230°-235° C. and underwent anexothermic polymerization process at 310°-320° C.

EXAMPLE 4 Synthesis of Star Branched Polyester-imide Based on theTrisanhydride II (R═CH₃)

To the solution of 32.4 g (0.3 mol) of 1,3-phenylenediamine in 750 ml ofN-methylpyrrolidinone cooled to 0° C. under N₂ the mixture of 82.8 g(0.1 mol) of the trisanhydride II (R--CH₃) and 49.2 g (0.3 mol) of5-norbornene-endo-2,3-dicarboxylic anhydride was added in 6 portions (3hours) and the reaction mixture was stirred at RT overnight. After that,500 ml of toluene were added and the solution refluxed until all thewater was eliminated. Toluene was distilled off and the solution stirredat 160° C. for 6 hours. After cooling, the solution was precipitated in6 liters of ice-water mixture. The precipitate was washed with water anddried in a vacuum oven at 110° C. IR of the product was similar to thatdescribed in Example 3. The obtained unsaturated ester-imide oligomerformed a clear melt at 240°-250° C. and underwent polymerization at315°-320° C.

EXAMPLE 5 Curing of an Epoxy Resin with the Trisanhydride I

10 g of the Bisphenol A based epoxy resin 6010 (CIBA-GEIGY) having anepoxy equivalent of 190 were mixed with 12.5 g of the trisanhydride I.According to DSC data, the crosslinking reaction started at 140° C. andhad the peak temperature of 180° C. The mixture was cured at 150° C. for1 hour, 180° C. for 2 hours and 220° C. for 5 hours. The cured resinshowed no glass transition (DSC) upon heating to 350° C.

EXAMPLE 6 Synthesis of Polyester-imide-amide

To a solution of 64.8 g (0.1 mol) of the trisanhydride I of Example 1 in500 ml of dry DMAC cooled to 0° C. under N₂, a solution of 60 g (0.3mol) of 4-aminophenylether in 500 ml of dry DMAC was added dropwise (3hrs). Then, a solution of 100.5 g (0.3 mol) of 4-nadicimido benzoic acidchloride in 600 ml of dry DMAC was added dropwise (5 hrs) at 0° C. andthe reaction mixture stirred at room temperature overnight. Then, 500 mlof toluene was added and the mixture refluxed until the water waseliminated. Toluene was then distilled off and the solution stirred at150°-155° C. for 4 hours. After cooling, the solution was precipitatedin 5 liters of cold water. The precipitate--yellow powder--was washedwith water 3 times and dried under vacuum at 80° C. The formulation ofthe amide-imide-ester structure in the product was confirmed by thepresence of the characteristic absorptions in the IR spectra at 3300,3050, 1783, 1748, 1375 and 717-721 cm⁻¹. The oligomer formed a clearmelt at 220°-230° C. and underwent an exothermic polymerization processat 310°-320° C.

Polymer structure: ##STR6##

What is claimed is:
 1. An aromatic trisanhydride of formula (I)wherein Ris hydrogen, C₁ -C₄ alkyl or aryl.
 2. An aromatic trisanhydrideaccording to claim 1 wherein R is aryl.
 3. An aromatic trisanhydrideaccording to claim 2 wherein R is selected from the group consisting ofphenyl, benzyl, α-naphthyl, β-naphthyl, meta- and para-methylphenyl andtrifluoromethylphenyl.
 4. An aromatic trisanhydride according to claim 3wherein R is phenyl.
 5. An aromatic trisanhydride according to claim 1wherein R is methyl.